Proper A/F ratio for the SHO?

[Diameg]

I am concerned that my LPM/80mm MAF setup is running me either lean or rich.
I sometimes have some dark smoke upon startup. Nothing major, but it is sometimes evident.
Plus, my gas mileage is poor (18 to 20 range over the last 15 tanks or so).
I know that dark soot inside the pipes is common but I get a lot.
I feel there is a loss of power in the 2500 to 3800 rpm range but the car screams above that.

The car does not throw any codes with the LPM/80mm out. With them in, I sometimes get the 411 code for the ACT. It is new.
The TPS is new.
Relatively new plugs, wires, O2 sensors. The IAC was cleaned thoroughly several times (and I've tried a new one to no avail).

Anyways, would those symptoms be consistent with running rich or lean?

And what is the proper A/F ratio supposed to be? I'm going to get mine checked soon.

 

[SHOnuff93]

black soot and poor mileage means its a bit rich. As for the a/f ratio, it should always be 14.7:1

 

[SHOfun 93]

I was told that the A/F should be 13.3? Was I told incorrectly?

 

[GreenBird]

14.7 is the absolute best ratio. at 14.7, all oxygen and all fuel will be consumed. since it is impossible to do day to day (or even hour to hour), you tune the car rich. rich is better than lean.